Retatrutide vs tirzepatide vs semaglutide: the numbers
Last updated November 10, 2026
One receptor, two receptors, three receptors. Each step up changed the average result. Here are the figures from the main trials, with their limits.
Three generations
Semaglutide activates GLP-1 only. Tirzepatide adds GIP. Retatrutide adds glucagon on top of both. GLP-1 and GIP mostly act on appetite and blood sugar. Glucagon is the piece tied to how much energy the body spends.
Average body-weight change at the top studied dose. Sources: STEP 1 (NEJM 2021), SURMOUNT-1 (NEJM 2022), retatrutide phase 2 (NEJM 2023). Separate trials, not a head-to-head comparison.
The table
| Molecule | Receptors | Trial | Weeks | Average change | Placebo |
|---|---|---|---|---|---|
| Semaglutide | 1 | STEP 1 | 68 | -14.9% | -2.4% |
| Tirzepatide | 2 | SURMOUNT-1 | 72 | -20.9% | -3.1% |
| Retatrutide | 3 | Phase 2 | 48 | -24.2% | -2.1% |
How to read it
These are separate trials with different participants and lengths, so the rows are not a strict ranking. The one direct comparison published so far is SURMOUNT-5, where tirzepatide averaged -20.2% against -13.7% for semaglutide at 72 weeks. Retatrutide has not been run head to head against either.
On this site the dual agonist is sold for research as GLP-2T and the triple agonist as GLP-3RT.